Author: Jenny List

3411 Articles

A Practical Discrete 386

November 27, 2022 by 36 Comments

There are some chips that no matter how much the industry moves away from them still remain, exerting a hold decades after the ranges they once sat alongside have left the building. Such a chip is the 386, not the 80386 microprocessor you were expecting but the LM386, a small 8-pin DIP audio amplifier that’s as old as the Ark. the ‘386 can still be found in places where a small loudspeaker needs to be powered from a battery. SolderSmoke listener [Dave] undertook an interesting exercise with the LM386, reproducing it from discrete components. It’s a handy small discrete audio amplifier if you want one, but it’s also an interesting exercise in understanding analogue circuits even if you don’t work with them every day.

A basic circuit can be found in the LM386 data sheet (PDF), but as is always the case with such things it contains some simplifications. The discrete circuit has a few differences in the biasing arrangements particularly when it comes to replacing a pair of diodes with a transistor, and to make up for not being on the same chip it requires that the biasing transistors must be thermally coupled. Circuit configurations such as this one were once commonplace but have been replaced first by linear ICs such as the LM386 and more recently by IC-based switching amplifiers. It’s thus instructive to take a look at it and gain some understanding. If you’d like to know more, it’s a chip we’ve covered in detail.

Unlocking A Locked-Down Inverter

November 25, 2022 by 21 Comments

There was a time when a mains inverter was a heavy, expensive, and not particularly powerful item, but thanks to switch-mode technology we are now spoiled for choice. Most inverters still work with 12 V or 24 V supplies though, so when [Chris Jones] was looking for one to run from 36 V batteries, he found a limited supply. Sadly the Greenworks model he ended up with was affordable, but locked to a particular battery by means of a serial line between battery and inverter. Buy the special battery? No, he did what any hacker would do, and modified the inverter to do without it.

Tracing the serial link led to a mystery chip, probably a microcontroller but without available data. It in turn had a line to an 8051 derivative that seemed to be the brains of the operation. Acting on a hunch he pulled down the line with a resistor, and as if by magic, a working inverter appeared.

As you might expect, here at Hackaday we abhor such tricks by manufacturers, and thus any moves to circumvent them are to be applauded. It would be extremely interesting were anyone to have the Greenworks battery to subject to some reverse engineering of the profile.

Meanwhile if this is a little complex for you, there is a much simpler way to make a rough and ready inverter.

It’s MacOS. On An Unmodified Wii!

November 24, 2022 by 17 Comments

We’re used to the so-called “Hackintoshes”, non-Apple hardware running MacOS. One we featured recently was even built into the case of a Nintendo Wii. But [Dandu] has gone one better than that, by running MacOS on an unmodified Wii, original Nintendo hardware (French, Google Translate link).

How has this seemingly impossible task been achieved? Seasoned Mac enthusiasts will remember the days when Apple machines used PowerPC processors, and the Wii uses a PowerPC chip that’s a close cousin of those used in the Mac G3 series of computers. Since the Wii can run a Linux-based OS, it can therefore run Mac-on-Linux, providing in theory an environment in which it can host one of the PowerPC versions of MacOS.

The installation sequence has more than its share of difficulties, but eventually he was able to get the Wii running MacOS 9, the last classic MacOS. It runs DOOM, Internet Explorer 5, and iTunes even on these limited resources, though the last package had display and sound issues. He then tries a MacOS X build, but without success.

It’s fair to say that this is not exactly a way to get your hands on a cheap Mac, and remains more of an exercise in pushing a console beyond its original function. But it’s still an interesting diversion, and maybe someone will in time make a MacOS X version work on the Wii too. If you’re curious about the Mac-in-a-Wii that inspired this work, you can see it here.

If Your Drone Flies, Eat It!

November 22, 2022 by 29 Comments

Over the years we’ve featured countless drone projects here at Hackaday, fixed wing, rotary wing, multi-rotor, and more. Among them all we think there may be a type that we’ve never seen, but that is about to change as it’s the first time we’ve brought you an edible drone.

Why might you need an edible drone, you ask? It’s not to conceal the evidence after closing an airport — instead it’s a research project from the Swiss Federal Institute of Technology to produce an efficient means of bringing sustenance to stranded climbers. The St. Bernard dogs are out of a job, it’s now done the modern way!

Jokes aside, this is clearly an experimental craft, a fixed-wing monoplane whose wings are made from rice cakes and gelatin. A stranded climber could certainly munch away at those airofoils, but we’re guessing a real device would need something a little more nutritious while retaining the light cellular structure.

This may be our first edible drone, but it’s not the first piece of edible technology we’ve brought you.

A Game Boy Advance – Downgraded!

November 21, 2022 by 6 Comments

We feature a large number of game console mods here, because enhancing the experience of using a classic machine often involves some really clever work. But here’s one that’s a bit different, instead of upgrading his Game Boy Advance, [Wenting Zhang] has downgraded it from a colour screen to a monochrome LCD. Take a look at the video below the break.

One might ask why this would be necessary, given that there are plenty of backlit colour LCD upgrades already for the GBA, but perhaps people who played the original might understand that it’s about improving the viewability over the rather poor-quality colour LCD original.

Interesting too is the choice of display controller. Where it might be expected to find an FPGA, instead there’s an PR2040. He goes into detail about its programming, and we hope it might inspire any others looking at screen transplants. Meanwhile if the name [Wenting Zhang] means anything to you, it should be for his other work with mono LCDs.

Continue reading “A Game Boy Advance – Downgraded!” →

Portable ESP32 RGB Lasershow Has All The Trimmings

November 21, 2022 by 47 Comments

Perhaps there was a time when fancy laser effects were beyond those without the largest of bank accounts, but today they can be created surprisingly easily. [Corebb] shows us how with a neat unit using an off the shelf RGB laser module and mirror module, driven by a ESP32 with software designed to make it as easy as possible to use.

The video below the break is in Chinese so you’ll have to turn on the subtitles if you’re an Anglophone, and it takes us through the whole process. It’s mounted in an SLA 3D printed enclosure which neatly holds all the parts. The ESP32 module drives a couple of DACs which in turn drive the galvanometer motors through a pair of amplifiers.

Then the software allows all sorts of custom displays for your creative expression, including uploading quick sketches over WiFi. Beyond pretty patterns we see it mounted on a bicycle for a head-up display of speed and navigation info. Even if it does fall off and break at one point we can see that could be an extremely useful accessory.

All the code can be found in a GitHub repository should you wish to try for yourself. Meanwhile we’ve covered a lot of laser projector projects here in the past, including most recently this one using stepper motors in place of galvanometers.

Continue reading “Portable ESP32 RGB Lasershow Has All The Trimmings” →

New Part Day: Exotic Filament For RF Dielectric Structures

November 20, 2022 by 10 Comments

The world of microwave RF design appears to the uninitiated to be full of unimaginably exotic devices, as engineers harness the laws of physics to tame radio signals to their will. Among the weapons in their arsenal are materials of known dielectric properties, from which can be made structures with the desired effects on RF that encounters them. This has traditionally been a difficult and expensive process, but it’s one now made much easier by the availability of 3D printer filaments with a range of known dielectric values.

It’s best to think of the structures which can be designed using these materials as analagous to Fresnel lenses we’re all used to in the light domain. The example piece given by Microwave Journal is a metasurface for use in a steerable antenna, something that would be a much more difficult piece of work by more traditional means.

Normally when we inform you of a new special filament we’d expect it to be more costly than standard PLA, but this filament is in a class of its own at 275 euros per kilogram. So the interest for most readers will probably be more in the technology than the expectation of use, but even then we can see that there will still be microwave experimenters in our range who might be tempted by its unique properties. We look forward to what is developed using it.

Via Microwave Journal. Thanks to [Eric Mockler] for the tip!